Looks like current incarnation is Stewart platform lookalike optical setup for all axes[1]. I misspoke in a different comment: Mine was older SpaceBall 5000 mod

Looks like current incarnation is Stewart platform lookalike optical setup for all axes[1]. I misspoke in a different comment: Mine was older SpaceBall 5000 model, and it was more like two joysticks joined at the stem. 1: https://www.fictiv.com/teardowns/spacenavigator-3d-mouse-teardown https://www.fictiv.com/teardowns/spacenavigator-3d-mouse-tea...